Fix the handling of sealed concrete classes

src/Reflection/Php/SealedAllowedSubTypesClassReflectionExtension.php

@@ -5,6 +5,7 @@
 use PHPStan\DependencyInjection\AutowiredService;
 use PHPStan\Reflection\AllowedSubTypesClassReflectionExtension;
 use PHPStan\Reflection\ClassReflection;
+use PHPStan\Type\ObjectType;
 use PHPStan\Type\UnionType;
 use function count;
 
@@ -30,6 +31,10 @@ public function getAllowedSubTypes(ClassReflection $classReflection): array
 			}
 		}
 
+		if ($classReflection->isClass() && !$classReflection->isAbstract()) {
+			$types[] = new ObjectType($classReflection->getName());
+		}
+
 		return $types;
 	}
 

tests/PHPStan/Rules/Classes/AllowedSubTypesRuleTest.php

@@ -44,6 +44,11 @@ public function testSealed(): void
 		]);
 	}
 
+	public function testSealedOnConcreteClass(): void
+	{
+		$this->analyse([__DIR__ . '/data/sealed_concrete.php'], []);
+	}
+
 	public static function getAdditionalConfigFiles(): array
 	{
 		return [

tests/PHPStan/Rules/Classes/data/sealed_concrete.php

@@ -0,0 +1,35 @@
+<?php declare(strict_types = 1);
+
+namespace SealedConcrete;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @phpstan-sealed a|b|c
+ */
+class s {}
+
+final class a extends s {}
+final class b extends s {}
+final class c extends s {}
+
+function foo(s $sealedClass): void
+{
+	if ($sealedClass instanceof a) {
+		return;
+	}
+
+	assertType('SealedConcrete\\s~SealedConcrete\\a', $sealedClass);
+
+	if ($sealedClass instanceof b) {
+		return;
+	}
+
+	assertType('SealedConcrete\\s~(SealedConcrete\\a|SealedConcrete\\b)', $sealedClass);
+
+	if ($sealedClass instanceof c) {
+		return;
+	}
+
+	assertType('SealedConcrete\\s', $sealedClass);
+}